In many cases it has been shown that feeding herbivores may induce defensive responses in plants. It also has been shown that conifers can attract parasitoids, so called bodyguards, that reduce the damage on the plant by harming or killing the herbivore or its ancestry. For the understanding of chemical communication mechanisms in tritrophic systems, one of the most intriguing questions is which differences between herbivore-induced and non-induced volatile blends are used by parasitoids to discriminate the “right” from the “wrong” blend (Mumm and Hilker, 2005).
Scots pine (Pinus sylvestris) is known to change the quantitative composition of its terpenoid volatile blend in response to egg deposition by the sawfly Diprion pini (Hymenoptera, Diprionidae). The oviposition-induced pine volatile pattern attracts the egg parasitoid Chrysonotomyia ruforum (Hymenoptera, Eulophidae), whereas mechanically wounded controls do not. In this study we aimed to elucidate the molecular mechanisms involved in the change of the terpene patterns by screening involved terpene synthases.